Icebergs breaking away from the Antarctic ice sheets every year contain enough water to fill the Three Gorges reservoir nineteen times, according to a study by Chinese scientists.

Researchers with the State Key Laboratory of Remote Sensing Science at Beijing Normal University analysed more than 10,000 satellite images from between 2005 and 2011, measuring for the first time all icebergs larger than one square kilometre detaching from the Antarctic coastline.

They estimated that about 755 billion tons of icebergs "calf", or break free, from the continent every year.

The volume of the Three Gorges reservoir on the Yangtze River, one of the world's largest, is less than 40 billion tons.

Their paper, “Ocean-driven thinning enhances iceberg calving and retreat of Antarctic ice shelves”, was published on the latest issue of the Proceedings of the National Academy of Sciences in the US.

The scientists warned that the collapse of the Antarctic ice shelf due to climate change could be worse than previously thought, and the study would shed new light on making more precise projections of future sea level rise.

“Iceberg calving from all Antarctic ice shelves has never been directly measured, despite playing a crucial role in ice sheet mass balance,” they wrote in the paper.

“Our results suggest that … iceberg calving may play an overlooked role in the demise of shrinking ice shelves, and is more sensitive to ocean forcing than expected from steady state calving estimates.”